1. Field of the Invention
The present invention relates, generally, to a fiber reinforced dental material for use in various restorative dental procedures and, more particularly, to a silane treated high purity chopped quartz fiber reinforced composite dental material which substantially addresses the difficulties in reestablishing interproximal contact, proximal voids, finishing, postoperative sensitivity and insufficient mechanical strengths associated with known composite materials.
2. Description of the Prior Art
Following the first introduction of posterior composites almost 40 years ago, there has been an increasing interest in its development by an esthetic-oriented patient population. The early attempts to replace silver resulted in numerous clinical failures, but the driving incentive had been created. Photocuring was a big step in reducing oxygen-inhibited polymerization that is hand mixed in during a chemical cure, which subsequently reduces strengths, and increases wear rates. During this development there has been some confusion in terminology. Microfills, actually 20-50 nanometer amorphous colloidal silica filled resins, were introduced to counteract excessive wear rates. But difficulties with high surface areas and Van der Waals forces of agglomeration prevented high filler loading due to uncontrollable thick viscosity consistencies. Nonetheless, microfill composites were easy to finish and prevented early particle "plucking" or pullout associated with larger particle filler. Soon strengths were improved with "hybrids" where larger particles were mixed in with colloidal silica. Polymerized high particle-filled composites were also ground down and mixed back into a resin paste with colloidal silica and known as "heterogeneous microfills." Currently, "universal composites" have reduced the average particle size by improving packing fractions and increased weight and volume percentages to a point where wear rates are now approaching those of silver fillings. Be that as it may, none of the particles employed in prior art particle-filled resins were ever larger than 100-200 microns. Indeed, excessively long fillers were summarily dismissed as being impractical for finishing purposes.
As an additional historical note, the progress of Bis-GMA and silane coupling combined with radiopaque barium glass filler initiated clinical trials and commercialization of tooth colored fillings for posterior teeth in the 60's. Although none of the early posterior Bis-GMA dental composite formulations were successful, significant improvements have come in stages to stimulate the use of dental resins to such an extent that they now rival amalgam as a restorative option. In fact, 23% of all dentists now indicate that composite is their material of choice for class II restorations.
Still many problems exist with the contemporary generation of posterior composites. They are still relatively difficult to handle, although experience and familiarity reduce this trouble. Concerns over, primarily, class II composite restorations have been highlighted recently through the American Dental Association, which described the most common complaints among practicing dentists. The primary objection is the inability to restore the proximal contact. Voids, particularly in the interproximal box, are a second area of criticism. Additional concerns are in the areas of finishing effort and the occurrence of post-operative sensitivity.